Exaggerated Startle Disease (ESD) (Hyperexplexia)
Exaggerated startle disease (ESD) is a genetic disorder also known as hyperexplexia in which babies have an exaggerated startle reaction. This disorder was recognized in 1962 when it was described by Drs. Kok and Bruyn as a disease with onset at birth, featuring hypertonia (stiffness), exaggerated startle response, strong brain-stem reflexes (especially head-retraction reflex) and, in some cases, epilepsy. The hypertonia disappeared during sleep and diminished over the first year of life. The startle reflex was sometimes accompanied by sudden stiffness causing the child to fall suddenly to the ground. There were 29 affected males and females in 6 generations of one family, indicating that the disorder is an autosomal (non-sexlinked) dominant trait. A number of other families have since been found with this disease.